15.2 Plants require nutrients table 15. 1 essential elements for most plants Element From available to plants Relative number of ions in dry plant material Macronutrients Nitrogen. N NO3, NH4 1,000,000 Potassium K 250,000 Calcium. Ca Ca2+ 125,000 Magnesium, Mg Mg2+ 80,00 Phosphorus, P H,PO4, HPO4 60,000 Sulfur s SO4 30,000 Micronutrients Chlorine, CI CH 3000 Iron. Fe Fe3t fel+ 2000 Boron. B H,BO3 2000 Manganese Mn Mn2+ 1000 Zinc Zn 300 Copper, Cu Cut. Cu2+ 100 Molybdenum, Mo Moo2 Measured relative to moly bdenum=1 Source: Salisbury and ross, plant physiology. Belmont, CA: Wadsworth, 198515.2 Plants require nutrients Element From available to plants Relative number of ions in dry plant material Macronutrients Nitrogen, N NO3 - , NH4 + 1,000,000 Potassium, K K+ 250,000 Calcium, Ca Ca2+ 125,000 Magnesium, Mg Mg2+ 80,000 Phosphorus, P H2PO4 - , HPO4 2- 60,000 Sulfur, S SO4 2- 30,000 Micronutrients Chlorine, Cl Cl- 3000 Iron, Fe Fe3+,Fe2+ 2000 Boron, B H2BO3 - 2000 Manganese, Mn Mn2+ 1000 Zinc, Zn Zn2+ 300 Copper, Cu Cu+ , Cu2+ 100 Molybdenum, Mo MoO4 2- 1 table15.1 essential elements for most plants Measured relative to molybdenum=1 Source: Salisbury and ross, plant physiology. Belmont, CA: Wadsworth, 1985